454 MR. P. L. SCLATER ON AN AUSTRALIAN DUCK. [May 16, 
1879 (on Sept. 24, Oct. 10, Oct. 11, Oct. 20, and Nov. 17, and one 
in 1880, Jan. 30); singularly enough, all these on-dissection turned 
out to be males. The skin of one of them only was in sufficiently 
good condition to be worth preservation. I now exhibit it, and a 
drawing (Plate XX XIII.) taken from it by Mr. Smit. 
I also exhibit the trachea of four of these individuals, showing a 
distinct bulla ossea, as is usual in the males of the Anatidee’. 
Having been in error myself as to my first identification of these 
Ducks, I fear I have also led Prof. Newton into an error upon the 
same subject. 
In January 1871 I furnished Prof. Newton with what I believed 
to be specimens (in the flesh) of a male and female Anas castanea 
that had recently died in the Society’s Gardens*. Prof. Newton, 
trusting to Mr. Baker’s determination that the presumed female was 
really of that sex, read a paper upon these birds before this Society 
in November of that year, in which he pointed out that the presumed 
female possessed the extraordinary peculiarity of having a bulla ossea, 
hitherto only known to occur in the male sex of the Anatide, and 
proposed in consequence the new generic term Virago for Anas 
eastanea*. But Prof. Newton having been kind enough to send me 
up the skins of this presumed pair of birds for examination, I think I 
may say that there is little doubt that Mr. Baker must have made 
an error in his determination of the sex of the supposed female, and 
that that bird is in all probability a male of Anas gibberifrons. 
This hypothesis is rendered more probable by the existence of the 
marked difference in the sternum between the two birds which Prof. 
Newton has pointed out, and by the fact that Mr. Ramsay tells us 
(Proc. Linn. Soc. N.S. W. iii. p. 154) that he has examined six 
females of Anas castanea without finding any trace of the bulda ossea. 
I fear therefore that the proposed generic term ‘‘ Virago” will not 
stand. 
I have not ascertained female specimens of Anas castanea, and 
cannot, therefore, say how that sex differs in plumage from A. gibbe- 
rifrons. But it will be at once seen on comparison that there is a 
considerable difference in the bills of the two species, that of A. 
castanea being considerably longer and larger than that of A. gibbe- 
rifrons, and that the presumed female of A. castanea (the type of 
Virago) agrees in this respect as well as in every other point with 
the male of A. gibberifrons. 
1 The trachea is very similar to that figured by Prof. Newton, P. Z. 8. 1871, 
p- 650, fig. 4. 
? The male was purchased June 15, 1870, and died Jan. 9, 1871; the 
presumed female arrived May 11, 1865, and died Jan. 7, 1871. 
* See P. Z. S. 1871, p. 650. 
